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Re: [Fwd: An Example for Unorder]

From: Drew McDermott <drew.mcdermott@yale.edu>
Date: Mon, 4 Oct 2004 02:34:35 +0000 (GMT)
To: public-sws-ig@w3.org
Message-ID: <E1CEIgt-0000bs-9e@frink.w3.org>


This is a response to a note by Naveen Srinivasan in another venue,
reposted here with this permission --

> From: Naveen Srinivasan <naveen@cs.cmu.edu>
> 
> Based on  our telecon discussion here is an example for unorder construct
> 
> Let us consider a composite process composed of 10 different smaller 
> processes, and each smaller process purchases an item. Let each of the 
> smaller process's process model consist of three parts, first 
> withholding $200 from the user's credit card, followed by actual 
> purchase (for simplicity let us assume that item's cost is less than 
> $200) and finally release the remaining of the $200 previously withheld.
> 
> Since there are no dependencies (atleast I/O wise) between the smaller 
> process, one can choose to model the above composite process as split or 
> split-join. Let us assume that the user's credit limit is $500 and the 
> total cost of all the 10 articles he is about to purchase is $75. In 
> this case both split and split-join will not succeed, because each of 
> the 10 process will try to block $200 and some process may fail.
> 
> On the other hand an Unorder process (based on Drew's definition) will 
> not fail because Unorder construct will not execute all the processes 
> concurrently rather executes them in no particular order.

I have always assumed that "unordered" meant that composite processes
could be interleaved.  Your interpretation seems to imply that the
unordered combination of process P_1,...,P_k is eqivalent to a random
ordered permutation of the P_i.  Have I misunderstood?

                                             -- Drew


-- 
                                             -- Drew McDermott
                                                Yale CS Department
Received on Monday, 4 October 2004 02:35:07 GMT

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